Wow...what a dumbass. With her kids in the car. Who the f@&k does she think she is. I would have lost my mind. Anyway... I have this same problem too. I find myself driving 10 mph faster usually than I did with my E60. You truly don't feel it as much in this car.
I have a cool idea I have always wanted to do. I wanted to take out the rear sunshade and put in white tape " why the f&$k are you n the left lane" or "move the f&$k over" . This would obviously apply after I passed them.